The Machine Type Communication (MTC) User Equipment (MTC UE) is also called a Machine-to-Machine (M2M) user communication equipment, which is a main application form of the Internet of things at the present stage. Low power consumption and low cost is an important guarantee for the MTC UE applied on a large scale. At present the M2M equipment deployed in the market is mainly based on a Global System of Mobile communication (GSM) system. In recent years, due to the improvement of spectrum efficiency of Long Term Evolution (LTE)/LTE-Advanced (LTE-A), more and more mobile operators select the LTE/LTE-A as an evolution direction of the future broadband wireless communication system. Multi-category M2M data services based on the LTE/LTE-A will also be more attractive. Only when it can make that the cost of the LTE-M2M equipment is lower than the cost of a MTC terminal of the GSM system, can M2M services be really switched to a LTE system from the GSM system.
At present, major alternative methods for reducing cost of the MTC user equipment include: reducing the number of receiving antennas of the terminal, reducing the baseband processing bandwidth of the terminal, reducing a peak rate supported by the terminal and using a half-duplex mode and so on. However, the cost reduction means the performance reduction, and the requirements for cell coverage of the LTE/LTE-A system cannot be reduced, thus an MTC terminal configured with low costs is required to take certain measures to achieve related coverage performance requirements of the LTE terminal. In addition, the MTC terminal may be located in places such as a basement and a corner and so on, the located scenarios are worse than that of a common LTE UE. In order to compensate the coverage reduction caused by the penetration loss, part of MTC UEs need higher performance improvement, thus, it is necessary to perform uplink and downlink coverage enhancement for part of MTC UEs with respect to this scenario. How to guarantee the user's access quality is a problem required to be firstly considered, and it is necessary to perform an enhanced design for a Physical Random Access Channel (PRACH) of the LTE/LTE-A system, to ensure that the MTC UE can access the system normally.
In the LTE/LTE-A system, location information of time-frequency resources occupied by a Random Access Response (RAR) message is contained in Downlink Control Information (DCI) and sent via a Physical Downlink Control Channel (PDCCH). Moreover, the above DCI information also includes a 16-bit Cyclic Redundancy Check (CRC), and the above CRC is scrambled with a 16-bit Random Access Radio Network Temporary Identity (RA-RNTI), and the scrambling mode is:ck=(bk+ak)mod 2 k=0,1,L,15
wherein, bk is the k+1th bit in the CRC; ak is the k+1th bit in the RA-RNTI; and ck is the k+1th bit generated through scrambling.
Since the enhanced design has been performed on the Physical Random Access Channel (PRACH) of the LTE/LTE-A system to ensure that the MTC UE can access the system normally, it is also required to perform the enhanced design for the Random Access Response (RAR) message of the LTE/LTE-A system, to ensure that the MTC UE can receive the message normally.